Fan blade and hub assembly



March 11, 1941. s PRESTON v 2,234,319

FAN BLADE AND HUB ASSEMBLY Filed Oct. 3, 1936 3 Sheets-Sheet 1 March 11,1941.

E. s. PRESTON FAN BLADE AND HUB ASSEMBLY Filed Oct. 5, 1936 5Sheets-Sheet 2 March 11,1941. 5 S O 2,234,319

FAN BLADE MID HUB AS SEMBLY 3 Sheets-Sheet 5 Filed Oct. 3, 1936IIIIIIIIZIIIIIII A L\\\\\\\\\\\\\ 'IIIIIIIIIIIIIIIIIIIIII 37110 flzggiPatented Mar. 11, 1941 FAN BLADE AND HUB ASSEMBLY Edward S. Preston,Hinsdale, Ill., assignor to Chicago Electric Manufacturing Company,Chicago, 111., a corporation of Illinois Application October 3, 1936,Serial No. 103,804

18 Claims.

My invention relates to a flexible bladed impeller (or fan blade and hubassemblage) particularly suited for use in household electric fans, andfor this purpose aims to provide an easily assembled and inexpensiveimpeller which will permit all of the blades to be integral parts of aninitially sheet-like blade member,'which will definitely determine thecurvature of radially extending blades, whichwill positively positionthe blades in balanced disposition, and which will present no sharpprojecting parts adapted to injure a hand striking the impeller.

In one of its fundamental aspects, my invention aims to provide animpeller construction of the above characteristics in which the radiallyextending blades are integral with a central blade-connecting part ofthe flexible sheet from which the blade member of the impeller isformed, and in which the blades are curved by fastening counterpartportions thereof to suitably formed portions of a rigid blade carrier,so that the assembly of this blade carrier with the blade member affordsa unit which in itself can be used as the impeller for an inexpensiveelectric fan. In this aspect, myinvention also aims to arrange such aunit so that the mere clamping of it to a stem by which it can berotated will cooperate with the said fastenings for maintaining theblades in balanced position without requiring other fastening elements.

In a second fundamental aspect, my invention aims to provide an impellerconstruction in which the aforesaid assembly is augmented by havingother counterpart blade portions of the said unit extend into spiralingand rearwardly open slots in a hollow member which conceals the saidfastened portions, so that the walls of the said slots cooperate indefining and maintaining the concaving of the blades, the slots beingarranged so that all blades can have their said other counterpartportions inserted in the said slots 'by a single movement of the saidunit with respect to the said hollow member. In this aspect, myinvention aims to permit the use of a simple hollow dome for the slottedhollow member, and to allow the use ofssuch a dome without having anyparts other than the effective blades to project from the convexexterior of the dome.

Instill another aspect, my invention aims to provide an impeller inwhich radially extending blades have portions thereof extending throughrearwardly open spiral slots in'a hollow member,

in whichv the blades also have other blade portions engaging the rearend of the said hollow member, and in which the last named bladeportions are clamped between the rear end of this member and a part of astem member which is adapted to be attached to a rotating shaft. Forthis purpose, my invention also aims to provide a 5 simple constructionof the just recited part of the-stem member which will also allow thatpart to bear directly against portions of the rear end of the saidhollow member, for the threefold purpose of increasing the rigidity ofthe assembly, excluding dust from the interior of the hollow member whenthe latter is a forwardly convexed dome, and modifying the concaving ofthe part of the blade adjacent to the leading edge of the blade.

Furthermore, my invention aims to avoid the following shortcomings ofheretofore proposed flexible bladed impellers suitable for use inhousehold electric fans:

(a) When such impellers have separately formed blades attached to acentral dome or the like, variations in the attaching of the severalblades, or slippage in case of lost play in the fastening means, is aptto unbalance the fan so as to cause it to vibrate when running.Moreover, any projecting parts of the fastening means may injure a handstriking the dome.

(b) If each blade has only a relatively narrow partextending through aslot in a dome, these narrow parts are apt to be inadequate for thestrains imposed on them when the fan is running, and particularly so ifthe assembly requires sharp bends in such parts;

(c) The separate attaching of each blade to'a. central dome or otherhubmember also'requlres skilled labor, thereby increasing the cost, andthe lay user generally is not competent for substituting a new blade incase one has become injured.

My present invention aims to overcome the above recited objections byproviding an impeller in which flexible blades extend through slots in adome which has no exposed blade-fastening parts or other elementsprojecting from its convex forward face; in which theclamping of eachblade extends over a quite wide part of the blade for adequatelydistributing the strain; and in whicheven a lay user can readilysubstitute a blade and blade carrier unit for a damaged one.

Illustrative of the manner in which I acc0m-'- plish the above recitedobjects;

Figs. 1, 2 and 3 are respectively front, side and rear elevation of anembodiment of my invention suitable for. use in household electric fans.

Fig. 4 is an enlarged front elevation of the blade member alone, as itappears when flat.

Fig. 5 is a more enlarged front elevation of the blade carrier which isdisposed in front of the central portion of the said blade member,showing the curved fingers to which the non-central perforated portionsof blade member are fastened for imparting a forward curvature to theblades.

Fig. 6 is a front elevation of the assembly of the blade carrier with'the blade member, drawn on the same scale as Fig. 4.

Figs. 7 and 8 are respectively front and side elevations of the spirally'slotted dome which is thereafter disposed in front of the bladecarrier,

drawn on the same scale as Fig. 5.

Fig. 9 is a fragmentary rear elevation of the resulting assemblage ofthe blade member, the blade carrier and the dome.

Fig. 10 is a perspective view of the clamping washer which is thereafterdisposed behind the said assemblage.

Figs. 11 and 12 are sections, respectively along the correspondinglynumbered lines in Fig. 1 but drawn on the same scale as Figs. 5 and 7,taken after the assembling of the impeller of Fig. 1 has been completedby forwardly inserting a shaftattachable stem into the previouslyrecited assembly and clamping the assembled parts into a. rigid unit bya screw extending rearwardly through the dome and into the said stem.

Fig. 13 is a fragmentary side elevation, similar to a part of Fig. 2 butdrawn on the same scale as Fig. 11, with one blade sectioned along theexterior surface of the dome.

Fig. 14 is a fragmentary front elevation of a more simple impellerembodying certain features of my invention.

Fig. 15 is anenlarged and fragmentary section taken along the line'l5--|5 of Fig. 14.

In my impeller, the blade member consists of four counterpart andconsecutively equally spaced blades B integral with and radiating from acentral blade-connecting part B the leading edge L of each blade beingdesirably chamfered as shown at b in Figs. 4 and 9. This blade member,which can readily be blanked out from a sheet of suitably flein'blerubber, has an L-shaped slot formed in it adjacent to the juncture ofthe inner ends of each two consecutive blades, with one shank of theL-formation extending radially part way toward a central perforation Cin the said member and the other shank extending from the inner end ofthe aforesaid'shank toward the leading edge of a blade. Thus arranged,each such slot defines the outer edges of a tab T which can readily beflexed and which tab is disposed within the dotted-line circle I shownin Fig. 4.

For a fan which is to blow air forwardly, each 6 blade is concavedforwardlyby fastening each such tab to a forwardly curved andcircumferentially extending finger F on a generally disklike metal bladecarrier A. which is shown separately in Fig. 5 and which has a centralperforation C corresponding in diameter to that in the blade member. Forthis purpose, the blade carrier is merely set against the forward faceof the blade member in suitable central and rotational alinement, andeach blade tab t is then flexed and fastened tothe corresponding carrierfinger by a rivet R extending through alined perforations p and p ofsaid tab and carrier finger, thereby forming-the initial assemblage ofFig. 6 in which thercarrier-fingers predetermine the concaving of eachblade about an axis H extending radially of the initially assembled fanmember.

This initial assembly can then be handled as a unit and rotated byany-suitable supporting means coaxial with it. Thus Fig. 15 shows thejust described unit as augmented by a stem member which includes'arearward portion 4 (axially bored for attachment to a rotating shaft)and a forward stem 6 which extends slidably through the said centralbores in the blade memberand the blade carrier, the blade member 'beingthereafter pressed rearwardly (by a nut N threaded on the forward end ofthe stem 6) so that the central portion of the blade carrier clamps thecentral portion B on the blade member against a peripheral flange 4aprovided at the forward end of the rearward portion of the stem member.

This flange preferably is at least as large in diameter as the part ofthe blade carrier around portions of which the fingers on that carrierextend, thereby affording a rigid assembly and one in which each bladeis :clamped' (partly by the fastening rivet and partly by the pressureof the stem flange 4a against it) for the entire circumferal length I2(Fig. 5) of the zone section from a part of which each carrier finger Fis formed. In practice, the nut N is preferably of a forwardly convexedshape, as for example illustrated conoidal shape, so that the airflowing past it aids in avoiding the creation of a vacuum near the axisof the said unit. Thus constructed, the just described simple andinexpensive unit has been found effective when constructed in smallsizes.

For larger sizes, I preferably supplement the above recited bladecurving action by also having a part of each blade, radially outward ofand near the radially outer edge of each carrier finger F, extendslidably also through a spiral slot 3 in a rearwardly open hollow memberwhich desirably is a forwardly convexed hollow metal dome D as shown inFigs. '7 and 8. Each of the said dome slots is curved to dispose itsrearward longitudinal wall in the same surface with the forward face ofa carrier finger F, and each such slot preferably is of-less length thanthe arcuate spread (along the dotted line M) of the blade part housed bythat slot, the bore of the dome being such that it will readily housetheblade terior diameter of the dome and having a central bore 8corresponding in diameter to the central perforations C and C in theblade carrier and the blade member. Next I provide a stem member whichhas its forward part B slidably insertable forwardly and consecutivelythrough the said central perforations in the washer, the blade memberand the blade carrier until the washer seats against a forwardly facingshoulder I (Fig. 12) at the juncture of the said stem part 6 with arelatively larger diametered rearward part 4 of the stem member. Thejust named rearward part desirably is axially bored forreceiving theforward end of a (not illustrated) rotating shaftand has a screw Sextending radially into it for gripping such a shaft;

Then I clamp the dome D rearwardly by a .screw 9 extending through anaxial' bore 2 in the dome and threaded into an axial bore-in the forwardend portion of the said stem member,.

thereby causing the dome to clamp the blade carrier and the blade memberconjointly against the washer W, and also clamping the washer rearwardlyagainst the said annular shoulder I.

If the washer were flat, the blade portions $13 of Fig. 13 which extendbeyond the corresponding slots and behind portions of the mouth end ofthe dome would space the washer from the parts vof the dome between theslot mouth, thereby marring the appearance and permitting dust to enterthe dome. To .avoid this when using blades which project laterally ofthe blades beyond the slot mouths, I preferably emboss equally spacedradially outward portions W of this washer rearwardly for a distanceclosely approximating the thickness of the rubber sheet from -'which theblade member was formed, eachsuch portion W having a. spread suflicientfor housing the portion of a blade which projects beyond the mouth endof one of the dome slots 3. Since this projecting blade part iscontiguous to an extension of the leading edge L of the blade, theflatwise clamping of that blade part against the mouth of the domeparticularly imparts firmness to the leading edge portions of the bladeand enables me to dispose these blade portions in a common plane, atright angles to axis of my impeller.

Each such rearwardly embossed portion of the washer preferably has itsrotationally rearward end W sloping rearward also, thereby avoiding asharp curving of the blade at the juncture of the parts of that bladewhich extend respectively into the adjacent dome slot and behind therear end of the dome, the other end W being disposed for engaging theadjacent edge of the blade for deflnitely fixing the rotational positionof the washer with respect to the dome.

'However, if the parts of the blades which extend through the slotscorrespond in width only to the lengths of the slots, it should beobvious without further illustration that a flat washer can be used,since this can then bear against all portions of the rear end of thedome excepting the mouths of the said slots.

With the elements of my impeller thus constructed and assembled, eachblade is substantially gripped over the entire width of the blade alongthe are if of Fig, 4, thereby distributing the strains so as to insure along life of the blade even if the portion of the blade outside the domeshould occasionally be severely flexed or twisted by the impact ofobjects against it. Indeed, the fastening of a part of each blade to acarrier finger cooperates with the clamping of another part of the sameblade between the dome and washer, so that each blade is effectivelyfastened and'definitely curved even when the blade part housed by theslot is not quite as thick as the width ofthe slot.

Moreover, the only permanent fasteningsnamely those of the blade tabs Tto the carrier ringers F-can speedily be made at the factory; and withan accurately contoured blade member the positive gripping of thismember, which is centered for that purpose by a part of the metal stem,allows the assembling of an accurately balanced impeller to be readilycompleted by unskilled labor, so that the entire manufacturing costislquite low.

In the completed impeller, the dome guides the air flow to avoidcreation of a vacuum near the axis of the propelled stream of air, andalso decidedly enhances the appearance of the impeller, particularlywhen the dome is of polished metal. Moreover, when the fastening screw 9has a rearwardly tapering head seated in correspondingly tapering domepart contiguous to the central perforation in the dome, no sharp partsof any kind project from the dome, so that even a child's hand will notbe injured by striking against this dome.

In Figs. 1 and 12, it will be noted that the washer or clamping flangeW, although formed separately from the axial stem of the impeller,serves the same purpose as the integral peripheral flange 4a on the stem4 in the more simple embodiment of Figs. 14 and 15. Hence the term stemmember, as used in certain claims, is to be understood as applyingregardless of whether such a flange or washer portion is integral withthe stem with which it is associated.

However, while I have heretofore described my impeller in connectionwith two embodiments each of which includes numerous desirable detailsof construction and arrangement, many changes might be made withoutdeparting either from the spirit of my invention or from the appendedclaims. 7 I

I claim as my invention:

1. In an impeller, a single-piece blade membe formed of flexiblematerial of generally uniform thickness, the said member comprising aplurality of counterpart and equally spaced blades radiating from acentrally perforated central porportion of the blade member, the saiddome having counterpart slots extending forwardly into' it from the rearend of the dome, the slots spiraling in the same direction rotationallyof the said dome; the said slots being equal in number to the saidblades, and each blade having a similar'portion thereof extendingthrough and engaging the forward end of one of the said slots; a stemmember coaxial with and extending forwardly through the centralperforation in the blade member and into the dome; and means associatedwith the said dome and stem for rigidly clamping the dome and thecentral part of the blade member to the said stem member.

2. In an impeller, a single-piece blade member formed of flexiblematerial of generally uniform thickness, the said member comprising aplurality of counterpart and equally spaced blades radiating from acentrally perforated central portion of the blade member; a forwardlyconvexed dome coaxial with the blade member and having its rear end oflarger diameter than the central portion of the blade member, the domehaving counterpart slots extending forwardly into it and spiraling inthe same direction rotationally of the dome, the said slots being'equalin number to the said blades, each blade having a similar portionthereof extending through'and engaging'the forward end of one of thesaid slots, and presenting an adjacent blade portion behind the dome; arigid blade carrier housed by the dome and having spaced portionsrespectively fastened to the several blades, the blade carrier having acentral portion bearing rearwardly against the central portion of theblade member; a stem member coaxial with the said dome and including ashank disposed rearwardly of the blade member and constructed forattachment to a rotating shaft;

and means interposed between the dome and the 4. An impeller comprisingan integral blade member formed of flexible and resilient material, thesaid member comprising a plurality of counterpart and equally spacedblades connected by and radiating from a central portion; a forwardlyconvexed metal dome having its mouth end coaxial with and of largerdiameter than the said central portion of the blade member; the domehaving counterpart slots of the same number as the said blades extendinginto it from its rear end, all of which slots spiral in the samedirection rotationally of the dome and opening at the rear end of thedome; each blade having a similar portion thereof extending through oneof the said slots and engaging the end of the slot through which itextends and having an adjacent portion projecting beyond the month endof the slot; a stem member coaxial with thesaid dome; and meansoperatively interposed between the dome and the stem member adapted tocause the said projecting parts of the blades to be clamped between therear end of the dome and a part of the stem member.

5. An impeller as per claim 4, including means housed by the dome andcentered by the stem member for rigidly spacing blade portions which aredisposed within the dome and respectively adjacent to,.the forward'endsof the said slots in the dome.

6. In a fan blade and hub assembly, an integral blade member formed offlexible and resilient material, the said member comprising a pluralityof counterpart and equally spaced blades connectedby and radiating froma central portion; a forwardly convexed metal dome having its rear endof larger diameter than the central portion of the blade member, thedome having spiral slots of the same number as the said blades extendinginto it from the mouth end of the dome, each blade having asimilar'portion thereof extending through one of the said slots-andengaging the end of the slot through which it extends each blade alsohaving a second portion thereof engaging a' rnouth end portion'of the.dome adjacent to the mouth'end of the slot through which the first namedportion of that blade extends; a stem member coaxial with the said domeand including a radial flange bearing forwardly against-the said otherparts of each blade; and means interposed between the dome and the stemmember for clamping the said second portions of the blades between theradial flange and the rear end of the dome.

7. An' impeller comprising in rigid assembly a single-piece blade memberof flexible material including counterpart blades radiating from acentral \blade-connecting part, a dome aligning axially with the slidcentral part and bearing rearwardly against a portion of each bladewhich is adjacent to the juncture of that blade with the nextrotationally forward blade; the dome having spiral slots, correspondingin number to the bIades extending forwardly into it and slopingforwardly rotationally rearwardly of the blades;

each blade extending through and engaging the forward end of one ofthe'said slots, whereby the spiraling of the slots twists the blades outof the plane of the central portion of the 'blade member; a stem membercoaxial with the dome and extending forwardly centrally. through theblade member, the stem member including a peripheral flange disposedbehind the said central bladeconnecting part and also behind the portionof each blade which is adjacent to the rear end of one of said domeslots, the last named means serving to draw the stem forwardly withrespect to the dome for uniting the heretofore recited elements in arigid assembly.

8. An impeller as per claim 7, in which each blade is of such width thata part thereof projects, in the direction in which the slot spiralsrearwardly, beyond the mouth end of the slot through which that slotextends, thereby disposing the said projecting blade part behind therear end of the dome; and in which the said flange has rearwardly offsetforward face portions respectively engaging the said projecting bladeparts to clamp these blade parts against the dome.

9. An impeller as per claim 7, including an auxiliary rigid memberhoused by the dome and having parts thereof rigidly fastened to bladeportions each of which is adjacent to the juncture of that portion ofthe blade with the next rotationally rearward blade; the said parts of'the rigid member being disposed so that each thereof curves the bladeporton fastened to it to substantially the same curvature as the forwardportion of the slot through which a part ofthe same blade extends,

;10. An impeller including in rigid assembly a flexible and single-pieceblade member comprising a plurality of counterpart and uniformly spacedblades radiating from a central bladeconnecting part, the said memberbeing integrally blanked from a sheet of flexible material; and

two cooperating menus for concaving each blade forwardly about an axisapproximately radially of the axis of the said blade-connecting part;one of the saidmeans being a forwardly convexed dome coaxial with thesaid blade-connecting part and provided with slots through which theblades respectively extend, each of the said slots spiraling in the samerotational direction; the other of the said means being a rigid bladecarrier freely housed by the dome and having rigidly connectedcounterpart portions each of which is fastened to a blade portionadjacent to the part of the same blade which extends through one of thesaid slots.

11. An impeller as per claim 10, inwhich the blade member is formed soas to present tab-like corner portions each of which is bent out of thegeneral plane of that member and constitutes one of the said fastenedblade portions.

12. An impeller as perclaim 10, in which the blade member is formed soas to present tab-like corner portions each of which is bent out of thegeneral plane of that member and constitutes one of the said fastenedblade portions, each such blades radiating from a centralblade-connecting part; a forwardly convexed blade-curvaturemaintainingdome coaxial with the said member and having counterpart spiral slotsextending forwardlyinto it from its rear end, all of which slots spiralin the same direction rotationally of the dome and through each of whichslots a part of a blade extends, the said blade part being adjacent tothe juncture of the blade with the next adjacent blade, and the blademember having an angular slot at each such juncture to permit the innerend of the trailing edge of the blade to be bent out of the common planeof the leading edges of the blades; a rigid blade carrier housed by thedome and having counterpart and spaced portions respectively fastened tothe parts of the blades which are thus adapted to be bent, the saidportions of the blade carrier being formed for holding each such bentpart of a blade in alignment with the slot through which another partextends; and means operatively interposed between the blade carrier andthe dome for maintaining the blade carrier in its said bladealigningdisposition with respect to the dome.

14. In a flexible-bladed impeller, a forwardly convexed dome havingcounterpart and equally spaced slots extending spirally into it from itsrear ends; a single-piece blade member comprising a central partconnecting the inner ends of counterpart blades of the same number asthe said blades, the said member being formedof a sheet of flexiblematerial corresponding in thickness to the width of the slots; and ablade-carrier coaxial with the blade member and insertible in the domeand having circumferentially spaced parts respectively fastened tocounterpart portions of the blades which portions are adjacent to thecentral part of the blade member; each of said parts of the bladecarrier sloping spirally at a pitch corresponding to that of one of theslots, whereby all of the said blades are adapted to be slidsimultaneously edgewise into the said slots by rotating the bladecarrier with respect to the dome; a stem member coaxial with the domeand including a radial flange extending behind a portion of each blade;and means interposed between the dome and the stern member for pressingthe said flange forwardly against the said blade portions to retain theblades in the said slots.

15. An impeller as per claim 7, in which each slot in the dome is ofless length than the width of the part of the blade extending throughthat slot, whereby each blade also presents a portion adjacent to themouth end of the corresponding slot and disposed behind the rear end ofthe dome; and in which the said flange has rear wardly offset portionsrespectively engaging the last named blade portions, and also has otherflange portions engaging the rear end of the dome.

16. An impeller as per claim 10, in which the hollow member is aforwardly convexed dome, and in which the said slots open at the rearend of the dome to permit the blade member to be attached to the domevby a forwardly spiraling movement during which the blades enter the saidslots.

17. An impeller as per claim 10, in which the hollow member is aforwardly convexed dome, and in which the said slots open at the rearend of the dome to permit the blade member to be attached to the dome bya forwardly spiraling movement during which the blades enter the saidslots; and in which the impeller includes a rotatable member extendingcoaxially with the dome through the dome, the blade carrier and thecentral part of the blade member for alining the last recited threeelements.

18. In a fan structure, a faring member having slots therein and shapedto the desired pitch angle for the fan blades and a fan blade memberhaving a plurality of flexible blades received in said slots, a covermember for said base of said faring member, a headed element and a screwthreaded thereinto, said headed element and said screw extending throughsaid faring member ,and said cover member and constituting tie means forholding them assembled relative to each other and as a means to retainsaid fan blades in said slots.

EDWARD S. PRESTON.

